If HA is enabled the the cluster will continue from the latest
externalized checkpoint.
Without HA it still start from the savepoint.
On 23/08/2020 16:18, Alexey Trenikhun wrote:
Let’s say job cluster was submitted as job from save point sp1, so
spec includes “-s sp1”, job run for days, takin externalized
checkpoints every 5 minute, then suddenly pod failed, Kubernetes job
controller restarts job pod using original job spec, which has “-s
sp1”, so Flink job will start from sp1 rather than from latest
externalized checkpoint. Is my understanding correct?
------------------------------------------------------------------------
*From:* Chesnay Schepler <ches...@apache.org>
*Sent:* Sunday, August 23, 2020 1:46:45 AM
*To:* Alexey Trenikhun <yen...@msn.com>; Piotr Nowojski
<pnowoj...@apache.org>
*Cc:* Flink User Mail List <user@flink.apache.org>
*Subject:* Re: Flink Job cluster in HA mode - recovery vs upgrade
A job cluster is submitted as a job, not a deployment.
The built-in Job controller of Kubernetes ensures that this job
finishes successfully, and if required starts new pods.
On 23/08/2020 06:43, Alexey Trenikhun wrote:
Since it is necessary to use cancel with save point/resume from save
point, then it is not possible to use Deployment (otherwise
JobManager pod will restart on crash from same save point), so we
need to use Job, but in that case ifJob pod is crashed who will start
new instance of Job pod ? Sounds like currently HA with kubernetes is
not achievable unless some controller is used to manage JobManager.
Am I right?
------------------------------------------------------------------------
*From:* Chesnay Schepler <ches...@apache.org> <mailto:ches...@apache.org>
*Sent:* Saturday, August 22, 2020 12:58 AM
*To:* Alexey Trenikhun <yen...@msn.com> <mailto:yen...@msn.com>;
Piotr Nowojski <pnowoj...@apache.org> <mailto:pnowoj...@apache.org>
*Cc:* Flink User Mail List <user@flink.apache.org>
<mailto:user@flink.apache.org>
*Subject:* Re: Flink Job cluster in HA mode - recovery vs upgrade
If, and only if, the cluster-id and JobId are identical then the
JobGraph will be recovered from ZooKeeper.
On 22/08/2020 06:12, Alexey Trenikhun wrote:
Not sure I that I understand your statement about "the HaServices
are only being given the JobGraph", seems
HighAvailabilityServices#getJobGraphStore provides JobGraphStore,
and potentially implementation of
JobGraphStore#recoverJobGraph(JobID jobId) for this store could
build new graph for jar rather than read stored graph from ZooKeeper?
Also, if there is single job with same job-id (job cluster),
jobgraph of failed job will be over written by new one which will
have same job-id?
------------------------------------------------------------------------
*From:* Chesnay Schepler <ches...@apache.org>
<mailto:ches...@apache.org>
*Sent:* Friday, August 21, 2020 12:16 PM
*To:* Alexey Trenikhun <yen...@msn.com> <mailto:yen...@msn.com>;
Piotr Nowojski <pnowoj...@apache.org> <mailto:pnowoj...@apache.org>
*Cc:* Flink User Mail List <user@flink.apache.org>
<mailto:user@flink.apache.org>
*Subject:* Re: Flink Job cluster in HA mode - recovery vs upgrade
The HaServices are only being given the JobGraph, to this is not
possible.
Actually I have to correct myself. For a job cluster the state in HA
should be irrelevant when you're submitting another jar.
Flink has no way of knowing that this jar is in any way connected to
the previous job; they will be treated as separate things.
However, you will likely end up with stale data in zookeeper (the
jobgraph of the failed job).
On 21/08/2020 17:51, Alexey Trenikhun wrote:
Is it feasible to override ZooKeeperHaServices to recreate JobGraph
from jar instead of reading it from ZK state. Any hints? I have
feeling that reading JobGraph from jar is more resilient approach,
less chances of mistakes during upgrade
Thanks,
Alexey
------------------------------------------------------------------------
*From:* Piotr Nowojski <pnowoj...@apache.org>
<mailto:pnowoj...@apache.org>
*Sent:* Thursday, August 20, 2020 7:04 AM
*To:* Chesnay Schepler <ches...@apache.org> <mailto:ches...@apache.org>
*Cc:* Alexey Trenikhun <yen...@msn.com> <mailto:yen...@msn.com>;
Flink User Mail List <user@flink.apache.org>
<mailto:user@flink.apache.org>
*Subject:* Re: Flink Job cluster in HA mode - recovery vs upgrade
Thank you for the clarification Chesney and sorry for the incorrect
previous answer.
Piotrek
czw., 20 sie 2020 o 15:59 Chesnay Schepler <ches...@apache.org
<mailto:ches...@apache.org>> napisał(a):
This is incorrect; we do store the JobGraph in ZooKeeper. If
you just delete the deployment the cluster will recover the
previous JobGraph (assuming you aren't changing the Zookeeper
configuration).
If you wish to update the job, then you should cancel it (along
with creating a savepoint), which will clear the Zookeeper
state, and then create a new deployment
On 20/08/2020 15:43, Piotr Nowojski wrote:
Hi Alexey,
I might be wrong (I don't know this side of Flink very well),
but as far as I know JobGraph is never stored in the ZK. It's
always recreated from the job's JAR. So you should be able to
upgrade the job by replacing the JAR with a newer version, as
long as the operator UIDs are the same before and after the
upgrade (for operator state to match before and after the
upgrade).
Best, Piotrek
czw., 20 sie 2020 o 06:34 Alexey Trenikhun <yen...@msn.com
<mailto:yen...@msn.com>> napisał(a):
Hello,
Let's say I run Flink Job cluster with persistent storage
and Zookeeper HA on k8s with single JobManager and use
externalized checkpoints. When JM crashes, k8s will
restart JM pod, and JM will read JobId and JobGraph from
ZK and restore from latest checkpoint. Now let's say I
want to upgrade job binary, I delete deployments, create
new deployments referring to newer image, will JM still
read JobGraph from ZK or will create new one from new job jar?
Thanks,
Alexey
